1. Field of the Invention
The present invention pertains to a power supply device, in particular, a power supply device having two AC power inputs, the power supply device being capable of choosing one of the two AC power inputs to be a power supply by determining the voltage level on the one of the two AC power inputs so as to maintain an uninterrupted power supply.
2. Description of Related Art
Most machine or instrument users would regard a power failure or unstable power supply as the most undesirable thing that could happen during the system operation, because it could cause severe damage to the system parts. In spite of the fact that a number of manufacturers claim that their uninterrupted power supply devices could protect users from possible power failure or unstable power supply conditions, most of these devices are based on the recharge-and-standby technology, which is hampered by the limited operating time of the device. Also, these power supply devices are designed with a single power input, but do not take into account what happens if the only power line experiences power failure or unstable power. As a result, a better solution is needed to deal with the above-mentioned problems, and that solution should be convenient to use and able to respond to the unstable power or power failure conditions.
To overcome these shortcomings, the present invention tends to provide a power supply device with two AC power inputs to mitigate and obviate the aforementioned problems.
The main object of the present invention is to provide a power supply device having two AC power inputs for giving a stable power supply, and when one of the two AC power inputs becomes unstable or cut off, the power supply device will automatically switch to the other AC power input thus preventing the problem of power interruption.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the attached drawings.